Just have a function that processes a limited number of records then calls itself with setImmediate to handle the next batch of records, that will give node time between each batch to handle i/o events.

@James JS can mimic "classical inheritance" but there is always a better way of solving the problem in JS. There are a few links to Eric Elliott's book on this page and I'd seriously recommend reading it, particularly the chapter on why classical inheritance is obsolete ;)